1. Field of the Invention
The present invention is directed to a system and an assembly, which includes operative components for implementing the system, wherein both the system and the assembly are structured and configured to modify and/or adapt a conventional diesel engine or diesel engine powered electric generator so that it can be operated in either a full diesel fuel mode or a bi-fuel mode, the latter fuel mode being defined by operating with a mixture of a preferably methane based gas and diesel fuel. Transferring between the two fuel modes occurs either automatically or manually while the engine operates continuously and without interruption in output. Additionally, the operation of the diesel engine or diesel engine powered electric generator in the bi-fuel mode results in efficiency levels comparable to those normally exhibited when operating in the full diesel fuel mode.
2. Description of the Related Art Diesel engines, both large and small, are commonly used articles of machinery employed to supply operating power for a variety of uses. These range from, for example, minor applications such as cars and trucks, home heating, and personal electric power generators, to major applications such as trains, heavy factory equipment, and large electric power generators such as those required to provide power to an entire facility or a power grid within a city. Moreover, it is the capacity of the diesel engine which dictates the output power to be achieved, and thereby dictates its potential uses.
In particular, diesel engine powered electric generators are well known in the art. While many types of electric generators having different power sources are available, including those that operate on hydrodynamic power, solar power, wind power, etc., a primary type of electric generator utilizes one or more diesel engines as the power source which permits the generation of electrical power. These diesel engine powered electric generators are indeed preferred because of the large electrical output which may be obtained. However, as previously indicated, the output of these electric generators is primarily dictated by the capacity of the diesel engines, and, therefore, because in many circumstances a very large electrical output is required, a number of diesel engine powered electric generators are often linked with one another in a parallel system so as to function together to provide the required output. Indeed, this capability is among the benefits of using diesel engine powered electrical generators.
Another significant reason diesel engines are preferred over other types of engines is the relatively lower cost of diesel fuel as compared with other fossil fuels for powering large capacity engines. Of course, however, although the cost is relatively low, there is still a substantial expense associated with powering diesel engines as the fuel consumption can be substantially great over an extended period of time, particularly when utilized to operate large electric generators. For this reason, it would be beneficial to provide a system which can reduce the amount of diesel fuel consumption without deteriorating the capacity of the diesel engine and/or harming or altering the diesel engine so as to hinder its normal operation. In particular, such a system should not require substantial modification and/or replacement of existing diesel engines, but should preferably work in conjunction with the existing models and designs so as to enhance their effectiveness and lessen the amount of diesel fuel to be consumed for a certain required capacity to be obtained.
A further consideration that must be addressed with the diesel engine powered electric generators involves the consistency of the electrical output. In particular, ideal circumstances require that a consistent electrical output level be maintained and/or that sufficient output to correlate with demand be consistently maintained. As a result, conventional systems cannot merely decrease the diesel fuel utilized within the diesel engines without suffering substantial negative effects as to the electrical power output. For example, a conservation type of system wherein lesser quantities of diesel fuel are utilized at certain periods of time will generally prove ineffective and as a result is not used, as such a pattern of operation typically leads to substantial irregularities in electrical power output. Furthermore, most diesel engine powered electric generators operate on a demand system which is truly not capable of working on a lessened diesel fuel supply without risking potentially serious damage to the diesel engine and/or generator themselves. Furthermore, dedicated, spark ignited natural gas generators are typically viewed as being less efficient and more expensive to operate. Accordingly, complete conversion to natural gas powered engines is also not desirable.
For the preceding reasons it would also be beneficial to provide a fuel system which can work in conjunction with existing high capacity diesel engines, but which can replace a portion of the diesel fuel utilized with an alternative, less expensive fuel. Such a system should not entirely remove the need for diesel fuel, but would maintain the output of the diesel engine with lesser quantities of the diesel fuel in order to assure a consistent capacity, based upon engine load, as would normally be obtained with a full diesel fuel operation, however, without the normal fuel consumption. Such a system, because of the potentially volatile nature of alternative fuel sources, should also provide a seamless operation that assures a consistent capacity within the usually accepted, optimal operating environment, and should be capable of detecting any potentially harmful disruptions in normal operation. Also, upon detection of any potentially hazardous conditions, the system should be capable of returning the diesel engine to normal, full diesel fuel operation without downtime or fluctuations in capacity. Further, such a system should be capable of incorporation with diesel engine powered electric generators of varying capacities, including those utilizing multiple diesel engines incorporated as part of a parallel system, without affecting the normal output parameters of those electric generators from when they are operating in their normal full diesel fuel mode. Additionally, such a system should operate without restricting normal air inflow to the engine to assure that engine operating efficiencies are maintained.
The present invention relates to a bi-fuel control system and retrofit assembly which may preferably be a digital control system and includes the operative components for implementing the system and assembly to modify a conventional, reciprocating diesel engine or diesel engine powered electric generator so that the engine is capable of operation in either a full diesel fuel mode or a bi-fuel mode. The bi-fuel mode may be more specifically defined as a mode of operation of the diesel engine or generator wherein the engine thereof is fueled by a mixture of a methane based gas and diesel fuel, instead of 100 percent diesel fuel for which the conventional diesel engine or diesel powered electric generator was originally designed. The term methane based gas comprises a variety of gaseous fuels including, but not limited to, methane, propane, butane, natural gas, bio-gas, well head gas, and/or mixtures thereof. The preferred methane based gas is natural gas wherein the bi-fuel mixture comprises a variable mixture of fuel containing from about 40 percent to 90 percent natural gas with the balance representing diesel fuel. The aforementioned percentage of natural gas utilized in the bi-fuel mode of operation more definitively represents the percentage of the ingredient of natural gas as part of the total fuel being consumed when the operation of the engine or generator is in the bi-fuel mode. In addition, the system and assembly of the present invention is specifically designed to be operative with all grades of diesel fuel including but not limited to diesel fuels No. 1, No. 2, No. 3 and heavy-bunker fuel, depending upon the normal capacity of the diesel engine or diesel powered electric generator.
As will be set forth in greater detail hereinafter, the digital bi-fuel control system and retrofit assembly of the present invention allows a conventional diesel engine or diesel engine powered electric generator, of the type set forth above, to automatically operate over the entire range of bi-fuel mixture percentages, including zero percent methane based gas, based on the value or values of any of any one or more pre-determined operating parameters indicative of the diesel engine load monitored during the operation of the diesel engine. Such predetermined, monitored operating parameters may include, by way of example only, engine intake manifold air pressure, gas control valve position, or kilowatt output of the generator.
Yet another factor in the design of the digital bi-fuel control system and retrofit assembly of the present invention is that the engine may be returned to full diesel fuel operation manually by the operator through the provision of a master on/off switch located at a main control panel associated with the unit. Moreover, of primary significance in the design and operation of the system and the retrofit assembly when applied to a diesel engine powered electric generator, is that either automatic or manual transfer between the bi-fuel mode and the full diesel fuel mode results in continuous, un-interrupted diesel engine operation and, therefore, generated electric power output.
The bi-fuel system and retrofit assembly of the present invention includes a gas control sub-system and sub-assembly designed for controlling the amount of methane based gas supplied to the diesel engine while operating in the bi-fuel mode, based on the load to the diesel engine. More specifically, in the illustrated embodiment, the gas control sub-system is designed to utilize a methane based gas having a preferred, predetermined gas supply pressure of between 1 psi and 5 psi. Of course, the ultimate gas pressure and/or flow rate may be varied depending on the system requirements. Furthermore, the functional operation of the gas control sub-system is scalable so that it can be adapted to various sized diesel engines requiring differing air and fuel flow rates. This of course includes engines or engine powered generators with multiple turbochargers and/or superchargers and/or multiple air intakes.
The digital bi-fuel control system and retrofit assembly of the present invention also includes an electronic control sub-system and sub-assembly which is designed to monitor various components of the overall system and further to control certain specific operative parameters of the system and the diesel engine which signify optimal and/or acceptable conditions for operation in the bi-fuel mode, based on the diesel engine load. The electronic control sub-system is further structured to display relevant system data and status which may directly affect the transfer of operation of the engine or generator between the bi-fuel mode and the full diesel fuel mode.
These and other features and advantages of the present invention will become more clear when the drawings as well as the detailed description, are taken into consideration.